It is proposed to investigate the influence of dietary fatty acids, particularly essential fatty acids, on the synthesis of triglycerides and glycerophosphatides in mammalian tissues. The role of essential fatty acids in lipoprotein synthesis will also be investigated in studies on the changes that take place in lipid and lipoprotein composition and associated enzyme activities during the development and regression of fatty livers caused by an EFA deficiency. A specific phase of these studies will involve the use of diets containing trans acids and studies will be conducted on the role of EFA and trans acids in function-structural properties of liver mitochondria. It is also proposed to investigate the relationship of the synthesis of prostaglandins to the biological functions and nutritional effects of essential fatty acids. The overall aim of the project is to gain further knowledge of the basic reactions in the synthesis of lipids and the importance of essential fatty acids in these reactions relative to the nutritional effects of dietary fats of different fatty acid composition.